What The Bible Says About Nonbelievers

"If thy brother, the son of thy mother, or thy son, or thy daughter, or the wife of thy bosom, or thy friend, which is as thine own soul, entice thee secretly, saying, Let us go and serve other gods, which thou hast not known, thou, nor thy fathers; Namely, of the gods of the people which are round about you ... Thou shalt not consent unto him, nor hearken unto him; neither shall thine eye pity him, neither shalt thou spare, neither shalt thou conceal him: But thou shalt surely kill him; thine hand shall be first upon him to put him to death, and afterwards the hand of all the people. And thou shalt stone him with stones, that he die." -- Dt.13:6-10.

He that sacrificeth unto [any] god, save unto the LORD only, he shall be utterly destroyed. Exodus 22:20.If you hear it said about one of the towns the LORD your God is giving you to live in that wicked men have arisen among you and have led the people of their town astray, saying, “Let us go and worship other gods” (gods you have not known), then you must inquire, probe and investigate it thoroughly. And if it is true and it has been proved that this detestable thing has been done among you, you must certainly put to the sword all who live in that town. Destroy it completely, both its people and its livestock. Gather all the plunder of the town into the middle of the public square and completely burn the town and all its plunder as a whole burnt offering to the LORD your God. It is to remain a ruin forever, never to be rebuilt. None of those condemned things shall be found in your hands, so that the LORD will turn from his fierce anger; he will show you mercy, have compassion on you, and increase your numbers, as he promised on oath to your forefathers, because you obey the LORDyour God, keeping all his commands that I am giving you today and doing what is right in his eyes. Deuteronomy 13:12-16

If there is found in your midst, in any of your towns, which the LORD your God is giving you, a man or a woman who does what is eil in the sight of the LORD your God, by transgressing His covenant,and has gone and served other gods and worshiped them, or the sun or the moon or any of the heavenly host,which I have not commanded,and if it is told you and you have heard of it, then you shall inquire thoroughly. Behold, if it is true and the thing certain that this detestable thing has been done in Israel,then you shall bring out that man or that woman who has done this evil deed to your gates, that is, the man or the woman, and thou shall stone them to death.On the evidence of two witnesses or three witnesses, he who is to die shall be put to death; he shall not be put to death on the evidence of one witness.The hand of the witnesses shall be first against him to put him to death, and afterward the hand of all the people. So you shall purge the evil from your midst. Deuteronomy 17:2-7

And the man that will do presumptuously, and will not hearken unto the priest that standeth to minister there before the LORD thy God, or unto the judge, even that man shall die: and thou shalt put away the evil from Israel.And all the people shall hear, and fear, and do no more presumptuously. Deuteronomy 17:12-13

But the prophet, which shall presume to speak a word in my name, which I have not commanded him to speak, or that shall speak in the name of other gods, even that prophet shall die. Deuteronomy 18:20

And whosoever shall not receive you, nor hear you, when ye depart thence, shake off the dust under your feet for a testimony against them. Verily I say unto you, It shall be more tolerable for Sodom and Gomorrha in the day of judgment, than for that city. Mark 6:11

I will therefore put you in remembrance, though ye once knew this, how that the Lord, having saved the people out of the land of Egypt, afterward destroyed them that believed not. Jude 15